1. Field of the Invention
This invention relates to electronic systems, and more particularly, to the packaging and connecting of integrated circuits in electronic systems.
2. Description of the Related Art
Pin counts for integrated circuits are rising for many types of devices, particularly those that are more complex (e.g., processors). The larger pin counts in turn require larger body sizes for such devices which in turn necessitates larger body sizes for integrated circuit packaging. However, the larger sizes for integrated circuit packaging results in various problems when mounted to a printed circuit board (PCB).
One significant problem for integrated circuit packages mounted on a PCB is expansion of the integrated circuit package relative to expansion of the PCB. During operation of the electronic system that includes the PCB and integrated circuit within a package, heat is generated. The generated heat causes expansion of both the integrated circuit and the PCB. If the PCB and integrated circuit package expand at different rates, strain is placed on the connections (e.g., solder joints) coupling the two. If the strain is severe enough, it may cause cracked or broken connections, which can lead to operational failures.
Other problems arise relating to signal integrity and power distribution. An increased number of signals to be conveyed between the PCB and the integrated circuit results in an increase of electromagnetic noise. This may result in crosstalk between various signal pins, which can adversely affect signal integrity. Power distribution to the integrated circuit must have low inductance and capability to transmit increasing amounts of power. Inefficient power supply will lead to transients (e.g. “ground bounce”, “simultaneous switching noise”) on the power bus. Such transients can cause erroneous operation of circuits within the integrated circuit.
One additional problem that this invention addresses is ability to easily and reliably replace an integrated circuit “chip” in order to upgrade or repair the system within which the chip and PCB reside.